I am now in search of a new desktop, wondering what specs i have to look for in order to make use of a good CPU.
On Intel side, your option is Core i9-13900K with DDR5-7200 CL34 RAM.
AMD has Ryzen 7950X with DDR5-6000 CL30 RAM.
The Intel one may load your file a lot quicker due to the faster RAM. But the AMD one may be faster at processing data and doing so with less electricity usage. Go with whichever one seems economical to you.
To be honest, I wouldn't expect these two to miraculously load your file in seconds. But if they do, that would be surprising. The slow loading time could be more of a software issue (for example, Microsoft Excel is pretty slow with huge files). The RAM on desktop PCs is much faster so you may definitely feel an improvement. Just don't expect a miracle.